When searching the library research databases or OneSearch, it's good to have a strategy. Unlike Google or Internet search engines, the databases and OneSearch can't interpret questions pasted in, natural language or strings of unconnected words. You should identify the key concepts in your thesis or research question and then brainstorm for a few alternative terms and synonyms that go along with them. Then you can connect and combine those terms in different ways using Boolean (see other boxes on this page).
This YouTube video from the University of Auckland, New Zealand demonstrates how to combine search keywords using the Boolean AND, OR, and NOT. It also shows you how Boolean works in a variety of database and search tool screens.
Boolean logic (named after mathematician George Boole) is a system of logic to designed to yield optimal search results. The Boolean operators, AND, OR, and NOT, help you construct a logical search. Boolean operators act on sets -- groups of records containing a particular word or concept.
The circle diagrams that help illustrate the relationships between the sets used in Boolean logic were named after another mathematician, John Venn. (The shading represents the outcome of the Boolean operation.)
When terms/concepts are combined with the AND operator, retrieved records must contain all the terms. For example: "Find reaction rates for mercury when temperature varies." This will retrieve citations that discuss all three concepts in each article. The more concepts you AND together, the fewer records you will retrieve.
The Boolean operator OR allows you to broaden a concept and include synonyms. For example, protons OR photons in radiation therapy will retrieve citations using either (or both) terms. This expands your search by retrieving citations in which either or both terms appear. The more concepts or keywords you OR together, the more records you will retrieve
The final Boolean operator NOT allows you to exclude concepts not relevant to your search. For example, you could search by using atoms NOT neutrons.
But be careful using this because you would eliminate records discussing atoms, as all articles discussing neutrons are eliminated.